1. Field of the Invention
The present invention relates to an adjustable anchor. The invention also relates to such an anchor for use in lift truck mast units.
2. Prior Art
Lift truck mast units commonly employ lift chains in pairs, the lift chains being trained over sheaves mounted upon a movable portion of a lift cylinder for raising a carriage relative to one upright portion of the mast. Adjustment of the anchor is necessary to ensure that the chains are under similar tension so that loads arranged upon the carriage are distributed equally by the parallel lift chains.
One particularly useful adjustable anchor for a lift truck mast unit comprise a housing including means attached to a base structure and means defining a bore arranged parallel to the adjacent end of a lift chain. The bore can preferably have a spherical taper formed about one end thereof opposite the adjacent end of the lift chain. Such an arrangement includes an adjusting sleeve arranged within the bore and having an outer diameter arranged in spaced-apart relation from the bore with a preferably spherically shaped, annular shoulder arranged for bearing engagement with the spherical taper on the housing, the sleeve extending through the bore toward the adjacent end of the lift chain, a peripheral portion of the sleeve being configured to facilitate its rotation within the bore, the sleeve further defining a threaded internal bore. In this arrangement a connector is secured to the adjacent end of the lift chain. The connector has a shank arranged in threaded engagement with the internal threaded bore within the sleeve. A lock nut is arranged upon the threaded shank for engagement with an end of the sleeve to selectively limit relative rotation between the sleeve and the connector.
It is clear that such an arrangement has many advantages. However, in practice and most particularly in the relatively rough usage to which lift trucks and similar equipment are exposed, it has been found that the lock nut will not adequately prevent relative rotation of the connector and the sleeve. In particular, it has been discovered that the sleeve will have a large tendency to rotate away from the lock nut.